"Upon review at the league office, we have found that a shot taken by Dallas' Monta Ellis with 16.0 seconds remaining in overtime was on the way down when initially contacted and ruled a block by Golden State's Jermaine O'Neal, and should have been ruled a goaltend," Rod Thorn, the NBA's president of basketball operations, said in a news release. "The exact trajectory of the ball when touched was impossible to ascertain with the naked eye, and the play was not reviewable."

The loss put the Mavericks (44-31) in ninth place in the loaded Western Conference, a half-game behind the Memphis Grizzlies and Phoenix Suns (both 44-30). A victory would have put the Mavs in seventh and a half-game behind the Warriors (46-28) for the No. 6 seed.

Referees also hurt the Mavericks' playoff chances by helping the Grizzlies at the end of Monday's victory against the Denver Nuggets. The Nuggets should have had 0.7 seconds left to try a desperation shot after an air-ball free throw, but the officials did not see it missed the rim. Thorn confirmed the missed call Tuesday.

The league is being more open about its officiating under new NBA Commissioner Adam Silver in an effort to improve transparency with fans, players and teams.